1: What is function of the following organelles
2: What is the endosymbiotic theory? What evidence supports it?
1:
- Nucleus: Controls cell activities and contains genetic material (DNA).
- Mitochondria: Produces energy (ATP) through cellular respiration.
- Endoplasmic reticulum: Involved in protein and lipid synthesis.
- Golgi apparatus: Modifies, sorts, and packages proteins for transportation.
- Lysosomes: Contain enzymes for breaking down waste and cellular debris.
- Vacuoles: Stores water, nutrients, and waste materials.
- Chloroplasts (in plant cells): Carry out photosynthesis to produce glucose.
- Ribosomes: Responsible for protein synthesis.
- Cell membrane: Regulates the movement of substances in and out of the cell.
- Cell wall (in plant cells): Provides structural support and protection.
2: The endosymbiotic theory proposes that certain organelles, such as mitochondria and chloroplasts, were once free-living prokaryotic organisms that became incorporated into ancestral eukaryotic cells through symbiotic relationships. This theory suggests that these organelles evolved from ancient prokaryotes that were engulfed by early eukaryotic cells and established a mutually beneficial relationship.
Evidence supporting the endosymbiotic theory includes:
- Mitochondria and chloroplasts have their own DNA, which is circular like that of prokaryotes.
- Mitochondria and chloroplasts replicate independently within cells, similar to prokaryotes.
- Both organelles have double membranes, which may have originated from the engulfing process.
- Mitochondria and chloroplasts produce their own proteins using ribosomes that closely resemble bacterial ribosomes.
- DNA sequence analysis has shown similarities between the genes of mitochondria and chloroplasts and those of bacteria.
- Cyanobacteria, which are similar to the ancestors of chloroplasts, can live as free-living organisms and also establish symbiotic relationships with other organisms.
1: The function of the following organelles are:
a) Nucleus: It houses and protects the cell's DNA, and controls the cell's activities by regulating gene expression.
b) Mitochondria: Produces energy for the cell through cellular respiration by converting nutrients into ATP.
c) Chloroplasts (found in plant cells): Converts sunlight, water, and carbon dioxide into glucose through the process of photosynthesis.
d) Endoplasmic reticulum (ER): Involved in the synthesis, modification, and transport of proteins and lipids.
e) Golgi apparatus: Modifies, sorts, and packages proteins and lipids for transport within or out of the cell.
f) Lysosomes: Contain enzymes that break down waste materials, cellular debris, and foreign substances.
g) Vacuoles: Store water, nutrients, and waste materials in plant cells, while in animal cells they are involved in various processes like storage, digestion, and excretion.
h) Ribosomes: Synthesize proteins by reading the mRNA transcript and joining amino acids together.
i) Cytoskeleton: Provides structural support to the cell, aids in cell movement, and helps maintain cell shape.
2: The endosymbiotic theory is a scientific hypothesis explaining the origin of eukaryotic cells, which states that certain organelles within cells, like mitochondria and chloroplasts, were once free-living bacteria engulfed by a host cell. Over time, they developed a mutually beneficial relationship, becoming fully integrated within the host cell.
Evidence supporting the endosymbiotic theory includes:
a) Mitochondria and chloroplasts contain their own DNA, which is similar to bacterial DNA.
b) They have their own ribosomes and are capable of independent protein synthesis, resembling bacterial ribosomes.
c) They divide independently within cells, similar to the way prokaryotic cells divide.
d) The size and structure of mitochondria and chloroplasts resemble those of bacteria.
e) Antibiotics that inhibit bacterial protein synthesis can also affect the protein synthesis of mitochondria and chloroplasts.
f) The genetic material within mitochondria and chloroplasts is more similar to that of bacteria than the nuclear DNA of eukaryotic cells.
g) Comparative genomics has revealed similarities between mitochondria/chloroplasts and free-living bacteria.
h) There is evidence of an outer membrane derived from the host cell, as well as an inner membrane derived from the engulfed bacteria in mitochondria and chloroplasts.